From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752658AbcLHNAo (ORCPT ); Thu, 8 Dec 2016 08:00:44 -0500 Received: from mx1.redhat.com ([209.132.183.28]:58288 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751888AbcLHNAm (ORCPT ); Thu, 8 Dec 2016 08:00:42 -0500 Subject: Re: [RFC PATCH] mm: introduce kv[mz]alloc helpers To: Michal Hocko , linux-mm@kvack.org References: <20161208103300.23217-1-mhocko@kernel.org> Cc: Andrew Morton , Vlastimil Babka , David Rientjes , Mel Gorman , Johannes Weiner , Anatoly Stepanov , LKML , Michal Hocko , Paolo Bonzini , Mike Snitzer , dm-devel@redhat.com, "Michael S. Tsirkin" , "Theodore Ts'o" , kvm@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-security-module@vger.kernel.org From: David Hildenbrand Organization: Red Hat GmbH Message-ID: <86cabb7a-1756-4d12-7ba4-776f66f6bb86@redhat.com> Date: Thu, 8 Dec 2016 14:00:20 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <20161208103300.23217-1-mhocko@kernel.org> Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Thu, 08 Dec 2016 13:00:27 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 08.12.2016 um 11:33 schrieb Michal Hocko: > From: Michal Hocko > > Using kmalloc with the vmalloc fallback for larger allocations is a > common pattern in the kernel code. Yet we do not have any common helper > for that and so users have invented their own helpers. Some of them are > really creative when doing so. Let's just add kv[mz]alloc and make sure > it is implemented properly. This implementation makes sure to not make > a large memory pressure for > PAGE_SZE requests (__GFP_NORETRY) and also > to not warn about allocation failures. This also rules out the OOM > killer as the vmalloc is a more approapriate fallback than a disruptive > user visible action. > > This patch also changes some existing users and removes helpers which > are specific for them. In some cases this is not possible (e.g. > ext4_kvmalloc, libcfs_kvzalloc, __aa_kvmalloc) because those seems to be > broken and require GFP_NO{FS,IO} context which is not vmalloc compatible > in general (note that the page table allocation is GFP_KERNEL). Those > need to be fixed separately. > > apparmor has already claimed kv[mz]alloc so remove those and use > __aa_kvmalloc instead to prevent from the naming clashes. > > Cc: Paolo Bonzini > Cc: Mike Snitzer > Cc: dm-devel@redhat.com > Cc: "Michael S. Tsirkin" > Cc: "Theodore Ts'o" > Cc: kvm@vger.kernel.org > Cc: linux-ext4@vger.kernel.org > Cc: linux-f2fs-devel@lists.sourceforge.net > Cc: linux-security-module@vger.kernel.org > Signed-off-by: Michal Hocko I remember yet another similar user in arch/s390/kvm/kvm-s390.c -> kvm_s390_set_skeys() ... keys = kmalloc_array(args->count, sizeof(uint8_t), GFP_KERNEL | __GFP_NOWARN); if (!keys) vmalloc(sizeof(uint8_t) * args->count); ... would kvmalloc_array make sense? (it would even make the code here less error prone and better to read) -- David